Conventionally, as shown in FIGS. 13(a) and 13(b), a substrate storage container includes a container body 1 that is provided with supporting ribs 2 that support semiconductor wafers, and a lid 4 that is detachably provided for an opening of the container body 1 and that has a sealing gasket 3 attached thereto, the lid 4 being provided with operation holes 5. The container body 1 is provided in a bottom portion thereof with a bottom plate 6 and in an upper portion thereof with a robotic flange 7. The bottom plate 6 may be provided on the bottom face thereof with positioning members 8 to position the substrate storage container at a predetermined position in a production line, a conveyer contact rail 9 to prevent the container from falling off which occurs when the container is conveyed on a conveyer, and the like. As shown in FIG. 13(c), the positioning members 8 of the substrate storage container each come into contact with a positioning pin P provided on a processing apparatus, etc., in a production line and, thereby, accurate positioning of the substrate storage container is executed. Thereafter, the lid 4 is opened and the semiconductor wafers are taken out of the container body 1 by an automatic machine, and the semiconductor wafers are processed. After the processing, the semiconductor wafers are stored in the container body 1 and the lid 4 is closed. In this manner, a substrate to fabricate highly integrated circuits is produced while micro dust is prevented from being adhered to the semiconductor wafer (see patent document 1).
For the above substrate storage container, the precision of the positioning by the positioning members is critically important for the productivity of the semiconductor wafers, etc. In the case where the positioning precision of the substrate storage container itself is insufficient, when the semiconductor wafers are taken out of or taken into the substrate storage container, the semiconductor wafers are broken, etc., because a hand unit of the automatic machine rubs or contacts the semiconductor wafers, resulting in the throughput of the semiconductor wafers being lowered.
In the above substrate storage container, the positioning members 8 are provided respectively at three positions on the bottom face of the bottom plate 6 so as to position the substrate storage container. The positioning members 8 each include a groove having a V-shaped cross section as shown in FIG. 13(c). The positioning pin P of the processing apparatus, etc., is guided along a slope of the groove that has a V-shaped cross section, so that the substrate storage container is adapted to be accurately positioned at a predetermined position.
To improve the positioning precision, it has been proposed that the positioning members of the substrate storage container be each provided with a centering section, into which the positioning pin fits, at the deepest portion of the groove having a V-shaped cross section or that the positioning be adapted to be executed accurately by the centering section by forming the centering section such that the centering section has an acuter angle than the angle of the slope of the groove having a V-shaped cross section (see patent document 2).
Patent document 1: Japanese Patent Application Laid-Open Publication No. 2005-064378
Patent document 2: Japanese Patent Application Laid-Open Publication No. 2002-353299